Why were castles built?

Question

Why were castles built?

Answer 1

To serve a fortress and protect the owners.

Answer 2

Why is this asked in Royalty? It belongs in History, surely?

To defend against attack.

Answer 3

Because wooden battlements were useless against cannons, fire, water, blades and strong winds.

Answer 4

Castles were actually walled cities  with a combination of stables for animals,a water supply,barracks for the soldiers, a great hall for eating and holding meetings,a chapel and buildings as living quarters for the locals.

But before the castle was built,the panic room was built first. In ancient times,kidnapping the local lord's family and holding them for ransom was a very profitable way to make a living.

The panic room had food,water,and a latrine  and most likely an escape route out of the castle that was only known to  the family  for security reasons.

But the ruler of the nation had to maintain control of the local population by placing a lord who was going to be loyal with the same religious,and political beliefs as the king. The castle was used to quarter the soldiers to defend against uprisings,or attacks from enemy soldiers as well.